MSC Nastran; Patran Tutorial - Normal Modes; Pshells and Cylindrical Coordinates

in this video I'll be performing in
normal modes analysis using P shells in
cylindrical coordinates full details of
this exercise are on page 400 of the PDF
linked in the video description below
I'll first start Patran and I'll create
a patch run database called prob 16 the
units for this example are in inches
pounds and PSI I'll click OK here on the
right I'll create a curve and the radius
of this round surface is 4 so type in 4
for the X start from the origin and then
I'll make a second curve that is 2
inches in length and if I scroll over
here you'll see the first curve has a
link before and if I I'm careful with
the mouse I can find the second curve
here or to better do this I can go to
label control turn on the curve number
and here you see I'm gonna hover over
the 2 or the middle of the entity it
automatically highlights that entity the
same thing for the other curve now I
have the rotate these about the z axis
so I can create my surface so under
geometry go to surfaces revolve create
surface revolve the total angle of
rotation is 360 degrees and this will
rotate about the third axis of
coordinate system 0 which is the z axis
I'll select this curve and that is my
surface here next I'll select surface or
curve to since the auto execute is on it
will automatically create my next
surface as soon as I click
another entity before moving on I'll
create my cylindrical coordinate system
using the three point method so here
you're select types on intrical accept
the defaults and hit apply and now you
can see my new coordinate system and
your properties go to isotropic from
material name call it mat for input
properties under elastic modulus type in
1 7 4 Poisson ratio it's 0.3 or Poisson
or your density is point zero zero zero
to 6 hit OK and click apply it to make
this material under 2d properties click
shell call this prop change standard
formulation to P formulation under input
properties select the material we just
made under thickness type in 0.25 inches
click OK
for your application region select the
surface click Add ok and apply
under load species will define element
uniform displacement I'll call this
support
our target element type is 2d my input
data will have an edge translation
restriction of 0 0 0 for the x y&z for
analysis coordinate frame 1 or this is
in this is not x y&z this is actually 1
2 & 3 and coordinate system 1 which is
cylindrical click OK for my application
region I'll simply select this outer
edge ad ok and apply going on to meshing
for my mesh seed I'll define a
requirement of 12 elements for the outer
curve and the inner curve once my mesh
sheet is done I'll select the surface
masher switch this to tria make the
topology truth 13 select the surface
surface 1 and hit apply
I have to go ahead and equivalence this
click equivalence and hit apply see the
pink markers indicating where duplicate
notes have been deleted I could then
analyze this by going to the analysis
tab analyze the entire model under
solution type switch this from my linear
static analysis to a normal modes
analysis under solution parameters we'll
switch the output format from X DB to
op2 click OK and hit OK here okay here
go into sub cases select this default
sub case under sub case parameters type
in number of desired routes 15 or
normalization methodist maximum hit ok
and apply click cancel and hit apply
it's and analyzes under opt I can input
the ob2 results I look at my results I
see it get a value of 726 Hertz
20:31 3740 300 and so on and I compare
this to the values they should get I'm
close to the values and the last time
this was performed they obtain the same
values I just showed you
to view the motes you can go to quick
pot French select this first one select
this French result select this
deformation result and click apply you
can see the mode shape here if I select
this next result I can view this mode
shape and if the match is obscuring the
view I can go to French attributes or I
should go to definitely deform
attributes and uncheck show and deform
so when I hit apply after that that
disappears if I wish to see the mesh on
the actual mode shape I can go back to
fringe attributes under display select
element edges and head apply now you see
the mesh on the mode shape and I can do
this for the other frequencies
you can see that they actually compared
to what they shown the example here and
the last one is the 10,000 Hertz let me
clean this up and one last comment if I
look at the coordinate system the notes
are using they're using the global
coordinate system I can modify them to
use the cylindrical system as shown here
go to modify object is node method azide
edit check these to select this
coordinate system for both pick all the
nodes hit apply when every analyzes I'll
call this one underscore to hit apply
when I realized this I should obtain the
same results so whenever and put the op2
file go to my results and notice that
one it kept the old results and to the
new results are at the bottom and here
you can see that I got the same values
when I switch the coordinate frames and
for simplicity I'll just review the last
one so this is the one using cylindrical
coordinates and this is the line using
the global system here and I obtain the
same mode shapes and frequencies you can
clean it up save and this concludes this
example